Re: [PATCH] net: caif: Fix a sleep-in-atomic bug in cfpkt_create_pfx

[David Miller]

From: Jia-Ju Bai <baijiaju1990@xxxxxxx>
Date: Sat, 10 Jun 2017 16:49:39 +0800

> The kernel may sleep under a rcu read lock in cfpkt_create_pfx, and the
> function call path is:
> cfcnfg_linkup_rsp (acquire the lock by rcu_read_lock)
>   cfctrl_linkdown_req
>     cfpkt_create
>       cfpkt_create_pfx
>         alloc_skb(GFP_KERNEL) --> may sleep
> cfserl_receive (acquire the lock by rcu_read_lock)
>   cfpkt_split
>     cfpkt_create_pfx
>       alloc_skb(GFP_KERNEL) --> may sleep
> 
> There is "in_interrupt" in cfpkt_create_pfx to decide use "GFP_KERNEL" or
> "GFP_ATOMIC". In this situation, "GFP_KERNEL" is used because the function 
> is called under a rcu read lock, instead in interrupt.
> 
> To fix it, only "GFP_ATOMIC" is used in cfpkt_create_pfx.
> 
> Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxx>

Applied and queued up for -stable.